Molecular dynamics of dissolution of a 36-chain cellulose Iβ microfibril at different temperatures above the critical pressure of water

Abstract

The cellulose dissolution is an essential pretreatment process for the chemical conversion of lignocellulosic biomass into biofuels. Here, the dissolution of a 36-chain Iβ cellulose model with a hexagonal cross-section (M36HCS) in water is analyzed by Molecular Dynamics (MD) with CHARMM36/TIP3P (C36/TIP3P) force field using gradual heating at 25 MPa. Our simulations showed that the dissolution of M36HCS starts to occur between 560 K and 600 K, which agrees with experimental observations. In our system, conditions near the critical point of water reveal that translational and rotational entropies decrease, while the low hydration level increases vibrational entropy. This investigation theoretically shows that C36/TIP3P adequately reproduces the dissolution of M36HCS even in high-pressure water as corroborated in reactors.